Referenced in: none

Automatically associated channels: Kir6.2

Title: The lung amiloride-sensitive Na+ channel: biophysical properties, pharmacology, ontogenesis, and molecular cloning.

Authors: N Voilley, E Lingueglia, G Champigny, M G Mattei, R Waldmann, M Lazdunski, P Barbry

Journal, date & volume: Proc. Natl. Acad. Sci. U.S.A., 1994 Jan 4 , 91, 247-51

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/8278374

Abstract
Water balance in the lung is controlled via active Na+ and Cl- transport. Electrophysiological measurements on lung epithelial cells demonstrated the presence of a Na+ channel that is inhibited by amiloride (K0.5 = 90 nM) and some of its derivatives such as phenamil (K0.5 = 19 nM) and benzamil (K0.5 = 14 nM) but not by ethylisopropylamiloride. An amiloride-sensitive Na+ channel of 4 pS was recorded from outside-out patches excised from the apical membrane. This channel is highly selective for Na+ (PNa+/PK+ > or = to 10). Isolation of a human lung cDNA led to the primary structure of the lung Na+ channel. The corresponding protein is 669 residues long and has two large hydrophobic domains. An amiloride-sensitive Na(+)-selective current apparently identical to the one observed in lung epithelial cells was recorded after expression of the cloned channel in oocytes. The level of the mRNA for the Na+ channel was highly increased from fetal to newborn and adult stages. This observation indicates that the increased Na+ reabsorption that occurs at birth as a necessary event to pass to an air-breathing environment is probably associated with control of transcription of this Na+ channel. The human gene for the lung Na+ channel was mapped on chromosome 12p13.